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Identifying and Location the Ecotone within the Dog River Watershed Hunter D. Griffin, Department of Earth Science, University of South Alabama, Mobile, AL 36688. Email: hdg92189@yahoo.com.

The main objective for this research was to identify and locate the ecotone within the Dog River Watershed, which is situated in the coastal community of Mobile, Alabama. Because Dog River is considered a tidal river, the ecotone is going to display a transition from a salt/brackish water environment to a freshwater environment. The main reason for conducting this research is because the ecotone of Dog River has never been located before. Therefore, the findings/data obtained from this research would be very beneficial because it creates a foundation that future researches can be based off. The method I used to identify the ecotone was through observation of the study area to point out indicators of a transition in vegetation. These indicators are displayed in the distribution and condition of plant species of the black needle rush and the bald cypress. The black needle rush is found in areas were salt/brackish waters are present, while cypress trees thrives best in areas dominated by freshwater. From this research, I was able to use the results to create a visual map showing the location of the ecotone within the Dog River Watershed. Key Words: Ecotone, Dog River Watershed, Environment, Tidal river, Saltwater, Brackish, Freshwater, Vegetation, Black needle rush, Cypress trees. Introduction

The goal of this research is to identify and located the ecotone associated with the Dog

River Watershed. An ecotone is defined as a transition zone between two types of environments

where species from both communities meet and integrate with one another (Traut, 2005). In this

transition zone there is a large abundance of different plant species competing to populate the

same location. The main reason for conducting this research is because the ecotone of Dog River

has never been located. Also, this research is important because it creates a foundation that opens

the door for future studies to see what this ecotone is actually doing.

The location of the Dog River Watershed is uniquely situated within the coastal

community of Mobile, Alabama. Because Dog River is located along the coast, it is

characterized as a tidal stream. This means that the water levels are influenced by the tide and

fluctuate frequently(Waldrop, 1974). Therefore, it is going to have a diverse environment that

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Figure 1: Example of ecotone with black needle rush and bald 

cypress in same location. 

displays both, a salt/brackish water environment and a freshwater environment. Therefore, the

type of ecotone associated with Dog River is one that displays the transition of vegetation from a

salt/brackish water environment to a freshwater environment. This type of ecotone is displayed if

figure 1, which show bald cypress and black needle rush present in the same location.

To locate this ecotone

there are two species of

vegetation I will use to study

the ecotone. These two

species of vegetation are the

bald cypress and the black

needle rush. The bald Cypress

is a great indicator of

freshwater vegetation because

these trees thrive in this environment. Also, the Cypress can live in areas with low salinity levels.

However, these trees found in areas of low salinity appear to struggle. The other type of

vegetation used for this research is the Black Needle Rush because it is a good indicator of a

salt/brackish water environment (Duncan, 1987). This plant is a good indicator of the ecotone

because it dominates salt/brackish water areas as well as areas on the edge of the ecotone where

salinity levels are low.

Research Question

Where is the location of the Dog River ecotone that identifies the transition zone from a

salt/brackish water environment to a freshwater environment?

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Figure 2: Data points collected using GPS. Shows bald cypress, black needle rush, and water samples.

Methods

The main method I used for

this research was with

observation of the study area.

For this, I used a Kayak to

travel the waterways of the

Dog River Watershed to

search for indicators that

showed a transition in

vegetation. The vegetation I

used as indicators was the

bald cypress and the black

needle rush. The reason I

used the bald cypress tree is

because if it showed signs of

struggle, then it proves there

is saltwater present,

identifying that as part of the ecotone. Also, I look at the black needle rush to identify areas with

a salt/brackish water environment. By locating the black needle rush, it will show how far up

stream saltwater can be found. Also, throughout these waterways I took water samples to check

the salinity levels present in the area. By recording the salinity levels it will give my finding

credibility that supports the location of the ecotone. Once I located these indicators I used a hand

held Garmin GPS device to mark these locations on a map. The points I marked with the GPS

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Figure 3: Location of ecotone

are shown in figure 2. These findings represent cypress trees, healthy or unhealthy, and areas that

contained black needle rush. I also marked locations were I took water samples.

Results

After

conducting my

research in Dog

River, my findings

allowed me to

identify and locate

the ecotone that

displayed a

transition from a

salt/brackish water

environment to a

freshwater

environment. These

results are shown in

figure 3, which is a

map of the located ecotone. Also, while searching for

indicators of the ecotone I took random water samples to check the salinity levels throughout

Dog River. The results of the salinity levels are shown in the graph of table 1. In this graph, I

recorded the average salinity levels found in each environment. The salinity levels were not used

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Table 1: Salinity levels

to map the ecotone. However, I used these results to backup my findings of the ecotones’

location.

Discussion / Conclusions

After conducting my research I

was able to identify and locate the

ecotone in Dog River. These results

are important because they now lay a

foundation for future research dealing with this issue. For instance, if someone wanted to do

future resea  rch associated with the Dog River ecotone, they now have a foundation to base their

research off. Therefore, through my findings I feel as if I have opened a new door for future

research.

Now that I have identified and located the ecotone in the Dog River Watershed, I think it

would be interesting and beneficial to do a research on the impact of saltwater intrusion. The

reason I would like to see this is because this was what I originally planned for my project to be.

However, I ran into the problem of not having anything to base my study off. This was because

the ecotone has never been located, until now. Therefore, in the future I would like to some kind

of research on saltwater intrusion to see if its’ had any serious impacts to the Dog River

Watershed. This is an important question to answer because the impacts caused by saltwater

intrusion don’t occur overnight, but take time for the real damage to be noticeable (Ranjan,

2007). However, once the damage has been done, it’s almost impossible to reverse it.

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Work Cited Attrill, M. J., S. D. Rundle. (2002). Ecotone or Ecocline: Ecological Boundaries in Estuaries.

Estuarine, Coastal and Shelf Science (2002), 55, 929–936 Retrieved: 8 April 2013. From: http://ac.els-cdn.com/S027277140291036X/1-s2.0-S027277140291036X-main.pdf?_tid=8c5653da-a8f8-11e2-92f1-00000aab0f27&acdnat=1366379803_8d10c011fbcc23da32e120eab653cc6a

Duncan, H. Wilbur and Marion Duncan (1987).Seaside Plants of the Gulf and Atlantic Coasts.Washington D.C. Smithsonian Institution Press.

Mohr, Charles. (1969). Plant Life of Alabama.Vol. 2. New York: Verlag Von J. Cramer. Ranjan, Priyantha, 2007. Effect of Climate Change and Land Use Change on Saltwater

Intrusion.Retrieved 26 February 2013.from: http://www.eoearth.org/article/Effect_of_climate_change_and_land_use_change_on_saltwater_intrusion

Traut, H. Bibit (2005). “The Role of Coastal Ecotones: A Case study of the Salt Marsh/Upland Transition Zone in California.” Journal of Ecology vol. 93 no. 2.Retrieved: 10 March 2013. From: www.jstor.org/stable/3599395

Waldrop, W. R., R. C. Farmer, and P. A. Bryant (1974). Saltwater Intrusion into a Flowing Stream. Technical Report no. 161. Coastal Studies Institute. Retrieved 3 March 2013. From: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740020781_1974020781.pdf